To clone and identify the gene encoding human ubiquitin binding enzym e 2 and study its expression pattern. Methods. According to the sequence of human EST, which is highly homologous to t he mouse ubiquitin binding/c...To clone and identify the gene encoding human ubiquitin binding enzym e 2 and study its expression pattern. Methods. According to the sequence of human EST, which is highly homologous to t he mouse ubiquitin binding/conjugating enzyme (E2), primers were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by bioinformati cs technique and its expression pattern was studied by using multiple tissue No rthern blot. Results. Two cDNA clones encoding human ubiquitin conjugating enzyme have been i solated and identified. Both containing the ubiquitin conjugating domain, the 2 cDNA clones are 88% identical in amino acid sequences and splicing isoforms to each other only with an exon excised to form the short sequence. They belong to a highly conserved and widely expressed E2 enzyme family. Northern blot shows th at they are expressed exclusively in adult human heart, placenta, and pancreas b ut no transcripts can be detected in brain, lung, liver, skeletal muscle or kidn ey. Conclusions. The gene encoding human ubiquitin binding enzyme is expressed under temporal control. As a key enzyme in the degradation of proteins, ubiquitin con jugating enzymes play a central role in the expression regulation on the level o f post translation.展开更多
Background The genes encoding adiponectin receptor 1 （ADIPOR1） and small ubiquitin-like modifier 4 （SUM04） have been linked to anti-atherogenic effects, but little is known about whether polymorphisms in the two g...Background The genes encoding adiponectin receptor 1 （ADIPOR1） and small ubiquitin-like modifier 4 （SUM04） have been linked to anti-atherogenic effects, but little is known about whether polymorphisms in the two genes, acting separately or interacting, affect risk of coronary artery disease （CAD） without diabetes. Methods We genotyped 200 CAD patients without diabetes and 200 controls without CAD or diabetes at three single-nucleotide polymorphisms （SNPs） in ADIPOR1 and one SNP in SUM04, which were chosen based on previous studies. Potential associations were also explored between these SNPs and clinical characteristics of CAD without diabetes. Results Risk alleles at three SNPs inADIPOR1 （rs7539542-G, rs7514221-C and rs3737884-G） and the G allele at SNP rs237025 in SUM04 significantly increased risk of CAD without diabetes, with ORs ranging from 1.79 to 4.44. Carriers of any of these four risk alleles showed similar adverse clinical characteristics. Compared with individuals with a CC or GC genotype, those with a GG genotype at rs3737884 were at significantly higher risk of CAD that affected the left anterior descending coronary artery （OR： 6.77, P = 0.009）, the right coronary artery （OR： 4.81, P = 0.028） or a relatively large number of vessels （P = 0.04）. Individuals carrying a risk allele at one or more of the three SNPs in ADIPOR1 as well as a risk allele at the SNP in SUM04 were at significantly higher risk of CAD without diabetes than individuals not carrying any risk alleles （OR： 5.82, 95% CI： 1.23-27.7, P= 0.013）. Conelusions SNPs in ADIPORl and SUMO4 are associated with elevated risk of CAD without diabetes, and SNPs in the two genes may interact to jointly affect disease risk.展开更多
Resistance to the chemotherapeutic drug 5'-azacytidine(5'-AZA)is a major obstacle in the treatment of patients with acute myeloid leukemia(AML).The uridine-cytidine kinase 1(UCK1)has an established role in act...Resistance to the chemotherapeutic drug 5'-azacytidine(5'-AZA)is a major obstacle in the treatment of patients with acute myeloid leukemia(AML).The uridine-cytidine kinase 1(UCK1)has an established role in activating 5'-AZA and its protein level is significantly downregulated in patients resistant to the drug.However,the underlying molecular mechanism for the reduced UCK1 expression remains to be elucidated.We demonstrated that the ubiquitin E3 ligase KLHL2 interacted with UCK1 and mediated its polyubiquitination at the K81 residue and degradation.We showed that deubiquitinase USP28 antagonized KLHL2-mediated polyubiquitylation of UCK1.We also provided evidence that ATM-mediated phosphorylation of USP28 resulted in its disassociation from KLHL2 and UCK1 destabilization.Conversely,UCK1 phosphorylation by 5'-AZA-activated ATM enhanced the KLHL2-UCK1 complex formation,Importantly,silencing KLHL2 or USP28 overexpression not only inhibited AML cell proliferation but also sensitized AML cells to 5'-AZA-induced apoptosis in vitro and in vivo.These results were no longer observed in USP28-deficient cells.展开更多
Background:Kirsten rat sarcoma(KRAS)and mutant KRAS^(G12D)have been implicated in human cancers,but it remains unclear whether their activation requires ubiquitination.This study aimed to investigate whether and how F...Background:Kirsten rat sarcoma(KRAS)and mutant KRAS^(G12D)have been implicated in human cancers,but it remains unclear whether their activation requires ubiquitination.This study aimed to investigate whether and how F-box and leucine-rich repeat 6(FBXL6)regulates KRAS and KRAS^(G12D)activity in hepatocellular carcinoma(HCC).Methods:We constructed transgenic mouse strains LC(LSL-Fbxl6^(KI/+);Alb-Cre,n=13),KC(LSL-Kras^(G12D/+);Alb-Cre,n=10)and KLC(LSL-Kras^(G12D/+);LSL-Fbxl6^(KI/+);Alb-Cre,n=12)mice,and then monitored HCC for 320 d.Multiomics approaches and pharmacological inhibitors were used to determine oncogenic signaling in the context of elevated FBXL6 and KRAS activation.Co-immunoprecipitation(Co-IP),Western blotting,ubiquitination assay,and RAS activity detection assay were employed to investigate the underlying molecular mechanism by which FBXL6 activates KRAS.The pathological relevance of the FBXL6/KRAS/extracellular signal-regulated kinase(ERK)/mammalian target of rapamycin(mTOR)/proteins of relevant evolutionary and lymphoid interest domain 2(PRELID2)axis was evaluated in 129 paired samples from HCC patients.Results:FBXL6 is highly expressed in HCC as well as other human cancers(P<0.001).Interestingly,FBXL6 drives HCC in transgenic mice.Mechanistically,elevated FBXL6 promotes the polyubiquitination of both wild-type KRAS and KRAS^(G12D)at lysine 128,leading to the activation of both KRAS and KRAS^(G12D)and promoting their binding to the serine/threonine-protein kinase RAF,which is followed by the activation of mitogen-activated protein kinase kinase(MEK)/ERK/mTOR signaling.The oncogenic activity of the MEK/ERK/mTOR axis relies on PRELID2,which induces reactive oxygen species(ROS)generation.Furthermore,hepatic FBXL6 upregulation facilitates KRAS^(G12D)to induce more severe hepatocarcinogenesis and lung metastasis via the MEK/ERK/mTOR/PRELID2/ROS axis.Dual inhibition of MEK and mTOR effectively suppresses tumor growth and metastasis in this subtype of cancer in vivo.In clinical samples,FBXL6 expression positively correlates with p-ERK(χ^(2)=85.067,P<0.001),p-mTOR(χ^(2)=66.919,P<0.001)and PRELID2(χ^(2)=20.891,P<0.001).The Kaplan-Meier survival analyses suggested that HCC patients with high FBXL6/p-ERK levels predicted worse overall survival(log-rank P<0.001).Conclusions:FBXL6 activates KRAS or KRAS^(G12D)via ubiquitination at the site K128,leading to activation of the ERK/mTOR/PRELID2/ROS axis and tumorigenesis.Dual inhibition of MEK and mTOR effectively protects against FBXL6-and KRAS^(G12D)-induced tumorigenesis,providing a potential therapeutic strategy to treat this aggressive subtype of liver cancer.展开更多
文摘To clone and identify the gene encoding human ubiquitin binding enzym e 2 and study its expression pattern. Methods. According to the sequence of human EST, which is highly homologous to t he mouse ubiquitin binding/conjugating enzyme (E2), primers were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by bioinformati cs technique and its expression pattern was studied by using multiple tissue No rthern blot. Results. Two cDNA clones encoding human ubiquitin conjugating enzyme have been i solated and identified. Both containing the ubiquitin conjugating domain, the 2 cDNA clones are 88% identical in amino acid sequences and splicing isoforms to each other only with an exon excised to form the short sequence. They belong to a highly conserved and widely expressed E2 enzyme family. Northern blot shows th at they are expressed exclusively in adult human heart, placenta, and pancreas b ut no transcripts can be detected in brain, lung, liver, skeletal muscle or kidn ey. Conclusions. The gene encoding human ubiquitin binding enzyme is expressed under temporal control. As a key enzyme in the degradation of proteins, ubiquitin con jugating enzymes play a central role in the expression regulation on the level o f post translation.
基金Acknowledgments This study was funded by the National Natural Science Foundation of China （81570323, 30972709, 81061120527, 81241082） and the 12th Five-Year National Program of the Ministry of Scientific Technology （2012BAI10B01）. We thank Liu M and Zhou L from Beijing Hospital for providing experimental data, the nurses from Beijing Anzhen Hospital for collecting specimens, and the study volunteers.
文摘Background The genes encoding adiponectin receptor 1 （ADIPOR1） and small ubiquitin-like modifier 4 （SUM04） have been linked to anti-atherogenic effects, but little is known about whether polymorphisms in the two genes, acting separately or interacting, affect risk of coronary artery disease （CAD） without diabetes. Methods We genotyped 200 CAD patients without diabetes and 200 controls without CAD or diabetes at three single-nucleotide polymorphisms （SNPs） in ADIPOR1 and one SNP in SUM04, which were chosen based on previous studies. Potential associations were also explored between these SNPs and clinical characteristics of CAD without diabetes. Results Risk alleles at three SNPs inADIPOR1 （rs7539542-G, rs7514221-C and rs3737884-G） and the G allele at SNP rs237025 in SUM04 significantly increased risk of CAD without diabetes, with ORs ranging from 1.79 to 4.44. Carriers of any of these four risk alleles showed similar adverse clinical characteristics. Compared with individuals with a CC or GC genotype, those with a GG genotype at rs3737884 were at significantly higher risk of CAD that affected the left anterior descending coronary artery （OR： 6.77, P = 0.009）, the right coronary artery （OR： 4.81, P = 0.028） or a relatively large number of vessels （P = 0.04）. Individuals carrying a risk allele at one or more of the three SNPs in ADIPOR1 as well as a risk allele at the SNP in SUM04 were at significantly higher risk of CAD without diabetes than individuals not carrying any risk alleles （OR： 5.82, 95% CI： 1.23-27.7, P= 0.013）. Conelusions SNPs in ADIPORl and SUMO4 are associated with elevated risk of CAD without diabetes, and SNPs in the two genes may interact to jointly affect disease risk.
文摘Resistance to the chemotherapeutic drug 5'-azacytidine(5'-AZA)is a major obstacle in the treatment of patients with acute myeloid leukemia(AML).The uridine-cytidine kinase 1(UCK1)has an established role in activating 5'-AZA and its protein level is significantly downregulated in patients resistant to the drug.However,the underlying molecular mechanism for the reduced UCK1 expression remains to be elucidated.We demonstrated that the ubiquitin E3 ligase KLHL2 interacted with UCK1 and mediated its polyubiquitination at the K81 residue and degradation.We showed that deubiquitinase USP28 antagonized KLHL2-mediated polyubiquitylation of UCK1.We also provided evidence that ATM-mediated phosphorylation of USP28 resulted in its disassociation from KLHL2 and UCK1 destabilization.Conversely,UCK1 phosphorylation by 5'-AZA-activated ATM enhanced the KLHL2-UCK1 complex formation,Importantly,silencing KLHL2 or USP28 overexpression not only inhibited AML cell proliferation but also sensitized AML cells to 5'-AZA-induced apoptosis in vitro and in vivo.These results were no longer observed in USP28-deficient cells.
基金supported by the National Natural Science Foundation of China(82370631)the Talent Foundations from Army Medical University(4174C6),the Chongqing Government(CQYC20220303727)to Xie CMthe National Natural Science Foundation of China(31900449)to Xiong HJ.
文摘Background:Kirsten rat sarcoma(KRAS)and mutant KRAS^(G12D)have been implicated in human cancers,but it remains unclear whether their activation requires ubiquitination.This study aimed to investigate whether and how F-box and leucine-rich repeat 6(FBXL6)regulates KRAS and KRAS^(G12D)activity in hepatocellular carcinoma(HCC).Methods:We constructed transgenic mouse strains LC(LSL-Fbxl6^(KI/+);Alb-Cre,n=13),KC(LSL-Kras^(G12D/+);Alb-Cre,n=10)and KLC(LSL-Kras^(G12D/+);LSL-Fbxl6^(KI/+);Alb-Cre,n=12)mice,and then monitored HCC for 320 d.Multiomics approaches and pharmacological inhibitors were used to determine oncogenic signaling in the context of elevated FBXL6 and KRAS activation.Co-immunoprecipitation(Co-IP),Western blotting,ubiquitination assay,and RAS activity detection assay were employed to investigate the underlying molecular mechanism by which FBXL6 activates KRAS.The pathological relevance of the FBXL6/KRAS/extracellular signal-regulated kinase(ERK)/mammalian target of rapamycin(mTOR)/proteins of relevant evolutionary and lymphoid interest domain 2(PRELID2)axis was evaluated in 129 paired samples from HCC patients.Results:FBXL6 is highly expressed in HCC as well as other human cancers(P<0.001).Interestingly,FBXL6 drives HCC in transgenic mice.Mechanistically,elevated FBXL6 promotes the polyubiquitination of both wild-type KRAS and KRAS^(G12D)at lysine 128,leading to the activation of both KRAS and KRAS^(G12D)and promoting their binding to the serine/threonine-protein kinase RAF,which is followed by the activation of mitogen-activated protein kinase kinase(MEK)/ERK/mTOR signaling.The oncogenic activity of the MEK/ERK/mTOR axis relies on PRELID2,which induces reactive oxygen species(ROS)generation.Furthermore,hepatic FBXL6 upregulation facilitates KRAS^(G12D)to induce more severe hepatocarcinogenesis and lung metastasis via the MEK/ERK/mTOR/PRELID2/ROS axis.Dual inhibition of MEK and mTOR effectively suppresses tumor growth and metastasis in this subtype of cancer in vivo.In clinical samples,FBXL6 expression positively correlates with p-ERK(χ^(2)=85.067,P<0.001),p-mTOR(χ^(2)=66.919,P<0.001)and PRELID2(χ^(2)=20.891,P<0.001).The Kaplan-Meier survival analyses suggested that HCC patients with high FBXL6/p-ERK levels predicted worse overall survival(log-rank P<0.001).Conclusions:FBXL6 activates KRAS or KRAS^(G12D)via ubiquitination at the site K128,leading to activation of the ERK/mTOR/PRELID2/ROS axis and tumorigenesis.Dual inhibition of MEK and mTOR effectively protects against FBXL6-and KRAS^(G12D)-induced tumorigenesis,providing a potential therapeutic strategy to treat this aggressive subtype of liver cancer.
